Superior-performance lithium–sulfur batteries: a face-centered-cubic-structure high-entropy alloy improves the bidirectional catalytic conversion of polysulfides/sulfides

Abstract

Herein, we demonstrate a face-centered cubic-structure cobalt–nickel–copper–manganese–molybdenum high-entropy alloy (CoNiCuMnMo-HEA) anchored on a reduced graphene oxide (rGO) substrate as a separator intercalation layer (CoNiCuMnMo-HEA@rGO) for lithium–sulfur batteries. The CoNiCuMnMo-HEA catalyst possesses abundant exposed polymetallic sites and exhibits a strong interaction with polysulfides on the (111) densest stacking surface. Experiments and theoretical calculations prove that Mn and Mo elements play a key role in the reduction process of polysulfides in CoNiCuMnMo-HEA, while Ni and Co are very important in the oxidation process of sulfides. Meanwhile, the presence of Cu element effectively regulates the redox process, which results in HEA exhibiting excellent bidirectional catalysis. As a result, the initial specific discharge capacity of a Li–S battery with the CoNiCuMnMo-HEA@rGO modified membrane can reach 1512.4 mA h g⁻¹ at a rate of 0.2 C. The attenuation rate of each cycle is only 0.055% after 1100 cycles at 3 C, and the coulombic efficiency remains above 91.94%.